It is narrated from Hazrat Abu Humaid (may Allah be pleased with him) that he brought a bowl of milk from the place Naqi’ to the service of the Prophet Muhammad (peace and blessings be upon him), which was not covered. The Prophet Muhammad (peace and blessings be upon him) said: Why did you not cover it, even if only with a piece of wood? Hazrat Abu Humaid (may Allah be pleased with him) further states that the Prophet Muhammad (peace and blessings be upon him) has instructed to tie the mouths of water skins and to keep the doors closed at night.